Cheers! Very usefulI'd recommend this, to at least get a feel for head tracking to see if you get on with it as it's not to everyone's liking. And it costs basically costs next to nothing, and very effective.
for sim racing I suggest you to try Facetracknoir before pourchasing trackir.
(I owned both solutions...)
In fact it is cheaper than trackir and works quite wel.
IMHO headtracking is very effective with one single 32+ curved screen.